Danny Alexander, 42, is chief secretary to the Treasury, and has been the MP for Inverness, Nairn, Badenoch and Strathspey since 2005. He’s leading the government’s campaign to keep the union intact. For more information on the benefits of staying in the UK, log on to www.youdecide2014.uk

Danny, in the referendum countdown, what do you think is the biggest challenge facing the No camp?
We have to work as hard as we can to get across the message that we have the best of both worlds as part of the United Kingdom. We have a strong Scottish parliament, we have the deep pockets of the United Kingdom, and we have to also demonstrate to people the risks of independence. You know, the nationalists’ case on the currency has collapsed into a total shambles, people are seeing now their oil projections are pie in the sky and therefore an independent Scotland would have a real difficulty affording the public services like the NHS that we rely on. We have to get those messages across and make sure that as many of our supporters as possible get to the polls on September 18th. I think our side of the argument has the momentum but we have to make sure that is converted to a strong majority when the referendum day comes.

Obviously, the NHS has been a key issue. The SNP claims that the only way to save the NHS from privatisation and further cuts is to vote yes. How would you counteract those claims?
The claims are false from start to finish. Responsibility for the NHS in Scotland is in one person’s hands, and one person’s alone – and that’s Alex Salmond. It’s the Scottish government that decides what happens in hospitals and doctors surgeries here in Scotland; that will continue after the referendum whatever the results. And the truth is, NHS spending by the UK government has been increasing year after year after year – that will continue in the future. So these are pure scare stories from a Yes campaign that is increasingly desperate, it’s losing the argument and it’s trying to scare people – and people shouldn’t be scared because the truth is that the Scottish NHS will continue to be the responsibility of the Scottish Parliament after a no vote, and money will keep increasing for the NHS across the UK it’s what everyone has pledged to do, it’s what the NHS needs. We all believe in the NHS as a great British institution – let’s not break it up, let’s not risk it by going to independence where there is less money to go around, so actually an independent Scotland would be less able to afford the NHS that Scotland needs than we can within the United Kingdom.

You hit upon a very key point of the SNP plans, which is the value of oil fields, and their accusations that the No side is undervaluing what’s there and the slice that they’ll get. How do you tackle that issue?
All of the independent forecasts are showing less oil revenue projected than the SNP do, their projections are massively optimistic. Just recently, Sir Ian Wood – who is probably the most respected figure in the entire oil and gas sector – has come out with his own figures, and saying that the nationalists are overestimating oil revenues by about 40%, that in fact we can expect much less tax revenue in the years to come. And it stands to reason – oil is a declining resource; we want to get most of it out that we can, but that means accepting that much less tax revenue in future. And of course if you wipe away the hyper-optimistic predictions that the SNP have based their case on, what you are left with is an independent Scotland where the gap between what we raise and what we spend is just getting wider and wider and wider, and the consequences will be higher taxes, public expenditure cuts, year after year under independence.

Currency. The debate has been going on for many, many weeks. Alex Salmond doesn’t seem to accept that he wouldn’t be able to use the pound and just join the Euro if he sees fit. What do you think is the best outcome should, unfortunately, there be a yes vote?
Well, I think the currency issue has become really clear for people. It’s clear that there isn’t going to be a currency. The rest of the UK wouldn’t agree to it, and frankly there wouldn’t be in the best interests of an independent Scotland either – so Alex Salmond has a responsibility to come out with a Plan B, but instead of doing what he should be doing and saying what his Plan B is, his currency argument is collapsing into a total shambles with one advisor saying it might be temporary, another advisor saying they might do this, another one saying they might do that – and I think it just goes to show how little homework the nationalists have done over the last 80 years, working up their case for independence. They really ought to have thought this through properly – and I think that if you want to keep the pound, the only way to do it is to keep the United Kingdom together. That’s the way the pound works, it works well for Scotland, the UK works well for Scotland, let’s not break it up.

Finally, if you had 30 seconds to convince an undecided voter, what would you say to them?
I’d say that, as part of the United Kingdom, we have the best of both worlds. We have a strong Scottish Parliament; the Scottish Parliament has power to take decisions on a whole range of aspects of our lives. But we also get the benefits of sharing – sharing money, sharing resources – the deep pockets that the United Kingdom has, and the credibility the United Kingdom has in the world economy in terms of influencing things in the globe that we rely on. So, the best of both worlds. Independence is a hugely risky, dangerous, uncertain proposition. What you care about is having prosperity, having a stronger economy, having a strong currency in future. The way to secure that is to keep the UK together.